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Computational Analysis of Aerodynamics Characteristics of High-Speed Moving Vehicle
Published in Chander Prakash, Sunpreet Singh, J. Paulo Davim, Characterization, Testing, Measurement, and Metrology, 2020
Pawan Singh, Vibhanshu Chhettri, Nitin Kumar Gupta
A spoiler is an automotive aerodynamic device, intended design function of which is to “spoil” unfavorable air movement across the body of a vehicle in motion, usually described as drag. Spoilers on the front of a vehicle are often called air dams, because in addition to directing air flow, they also reduce the amount of air flowing underneath the vehicle, which generally reduces aerodynamic lift and drag. They are often fitted to race and high-performance sports cars, although they have become common on passenger vehicles as well. Some spoilers are added to cars primarily for styling purposes and have either little aerodynamic benefit or even make the aerodynamics worse. The goal of many spoilers used in passenger vehicles is to reduce drag and increase fuel efficiency.
Fluid Flow
Published in Daniel H. Nichols, Physics for Technology, 2019
Turbulent flow can be used to your advantage when keeping a car firmly on the road at high speeds. A spoiler changes the laminar flow over the car to turbulent flow to keep the car from lifting off the road like an airplane (Figure 9.6).
Multi-objective optimisation of drag and lift coefficients of a car integrated with canards
Published in International Journal of Computational Fluid Dynamics, 2020
Hamed Bagheri-Esfeh, Mohammad Rostamzadeh-Renani, Reza Rostamzadeh-Renani, Hamed Safihkani
Diffusers are one of the most prominent add-on devices that are attached to the lower part of rear bumper and control flow separation at back of the vehicle. Kang et al. (2012) tested the performance of a diffuser device by a CFD simulation using the ANSYS Fluent commercial software. By studying different sizes of diffusers, they could decrease the drag coefficient of a car model by 4.1%. Cheng and Mansor (2016) studied aerodynamic effect of rear-roof spoiler on a hatchback car model. By adjusting the rear-roof spoiler angle from −15° to 15°, they could reduce the drag coefficient by 2.9% in the optimal condition. Das and Riyad (2016) explored the effect of rear spoiler at various angles on a car model numerically. By changing rear spoiler angle in the model, drag and lift coefficients were reduced to 0.26 and 0.072, respectively that improved the car stability.
Evaluation of finite element human body models for use in a standardized protocol for pedestrian safety assessment
Published in Traffic Injury Prevention, 2019
William Decker, Bharath Koya, Wansoo Pak, Costin D. Untaroiu, F. Scott Gayzik
The 50th percentile male simplified pedestrian model (M50-PS; height, 175 cm; weight, 74.5 kg), 6-year-old (6YO-PS; height, 117 cm; weight, 23.4 kg), 5th percentile female (F05-PS; height, 150 cm; weight, 50.7 kg), and 95th percentile male (M95-PS; height, 190 cm; weight, 102 kg) were simulated through the suite of cases for a total of 48 simulations (3 speeds by 4 vehicles for 4 models). The impacting vehicles included a family car (FCR), multipurpose vehicle (MPV), roadster (RDS), and sports utility vehicle (SUV), each simulated at 30, 40, and 50 km/h. A visual of the M50-PS positioned with the FCR is shown in Figure 2. The shape and stiffness of these vehicle models were derived from 11 vehicle models from 5 different car manufacturers. Each vehicle model was defined with deformable components (spoiler, bumper, grill, bonnet) and rigid components (windscreen and roof; Klug et al. 2017). These 4 publicly available standardized generic vehicles and boundary conditions for each simulation were provided by TU Graz, Vehicle Safety Institute as part of the Coherent Project. A segment-based contact was defined between the vehicle and the outer surface of the HBM, with both dynamic and static friction coefficients set to 0.3. As per TB-024, mass scaling and time step settings should be chosen so that they can also be used for generic vehicle check and assessment of deployable system simulations. The time step for the simulations in this study was set to 4e-4 ms. All simulations were conducted in LS-Dyna R.7.1.2 and were simulated on 44 cores.
Head injury criteria in child pedestrian accidents
Published in International Journal of Crashworthiness, 2018
D. Montoya, L. Thollon, M. Llari, C. Perrin, M. Behr
The pedestrian model used is the six years model of the pedestrian ellipsoid family marketed by MADYMO and validated in impact situations [11]. This validation includes a large range of PMHS impactor tests on various body parts, blunt impact tests and car pedestrian tests. Moreover, European new car assessment program (EuroNCAP) adopted a Pedestrian Testing Protocol for the assessment of active bonnets and the MADYMO ellipsoid pedestrian human models have been accepted as a numerical tool in this protocol. It was developed using anthropometric specifications from the Q-series of child dummies (standing height, sitting height, shoulder width, knee height and weight). This model allows direct calculation of the HIC for the head segment. This model is made of 52 rigid bodies and 64 ellipsoidal surfaces, and represents the 6-year-old child 50th percentile. Contacts between the front structure of the vehicle and the pedestrian are defined using force/deformation functions. The vehicle model consists of seven ellipsoids representing the spoiler, the bumper, the grill, the hood, the windshield, roof and the wheels. For each ellipsoid except windshield and wheels, which are not concerned in child impacts, force-deflection functions were implemented: one function is for the hood and was computed from the child headform tests, one is for the grill and was computed from the upper legform tests and one is for the spoiler and the bumper and was computed from the legform tests. In order to be representative of our vehicles, we applied the corresponding functions derived from subsystem trials published by EuroNCAP in the APROSYS SP3 project [13]. This allowed applying to each front of the vehicle model the average mechanical behaviour measured on actual vehicles.